You would abide by whatever your agreement was. If you claim that the agreement was that utilities be shared by the people actually living in the apartment, and she claims that you were supposed to pay a share whether or not you lived there as long as the lease continues, you can both argue your positions to the judge if and when she sues you. The judge will then decide.

If you're living there, keeping your stuff there, insisting on your right to enter at all times, you don't really have much of an argument for why you shouldn't share in the utilities.